Lighting devices based on solid state lighting technology which comprise a wavelength converting layer are known in the art, such lighting devices are referred to as light converting devices. The wavelength converting layer enables the use of more efficient light sources which, in use, do not emit light of a desired color. The wavelength converting layer converts the emitted light from the light source into the desired color. However, it is often required to protect the surface of the wavelength converting layer with a protective coating, and as the material of the protective coating has a different refracting index than the surrounding air, the spectrum of the light emitted from the light converting device is therefore altered due to refraction in the interface between the wavelength converting layer and the protective layer. This can be counteracted by altering the spectrum of the light emitted, in use, by the light source, or by altering the refractive index of the wavelength converting layer. However, different materials each have their own refractive index and the light converting device thus has to be tuned for different material, adding cost and complexity to the product and the process.
U.S. Pat. No. 8,575,646 proposes the use of a hydrophobic surface to control wetting for the purpose of creating a lens of silicone for a device having a solid state light source. This construction provides no solution to the above problem.
Hence, there is still a desire to find a solution which improves light converting devices to provide a desired spectrum of emitted light without significant modifications so that addition of unnecessary costs and complexity to the production process is avoided.